The sleep of healthy 50-60 year old subjects is being studied. Forty females and forty males provide self-reports of their-sleep, maintain sleep-diaries for three weeks and report on each previous night's sleep. Electroencephalic recordings of sleep are obtained for five nights. A series of cognitive and personality status tests are administered. The interrelations of the sets of measures are analyzed. The data of the males and females of these samples are compared and further compared with healthy young adults.